Engine cylinder burnishing device



Jan. 30, 1934. J. sUNNEN ENGINE CYLINDER BURNISHING DEVICE Filed April 30, 1932 HTTo/PMEY reame 13.11.130, 1934 NrrED erf-Ares PATENT oFFie ll Claim.

My invention has relation to improvements in burnishing devices for engine cylinders and vitconsists in the novel features'of construction more fully set forth in the specification and pointed out g in the claim.

The .invention is particularly adapted for finishing operations on engine cylinders that are being restored to serviceable condition by grinding or honing; and it consists in providing a w burnishing brush or set of brushes for arrangement on a rotatable holder which is inserted Vwithin the cylinder and actuatedto cause the brushes to scrub and burnish the cylinder wall.

Grinding stones, or hones, operate, as is well known, by abrasion, and when a cylinder is reconditioned by grinding, sharpabrasion scores remain on the wall of the cylinder, even though a relatively ne stone is used for the final grinding operation. If the cylinder is true these scores are tolerated because they are uniformly distributed over the entire cylinder wall. However, the presence of the abrasion marks prevents a newly 'ground cylinder from functioning at its maximum eniciency until after it has been operated a certain length of time, or worn in. Of course, during this Wearing in, or smoothing operation, excessive Wear comes on the piston rings so that they are seriously damaged by the time the cylinder wall has been Worn smooth.

My invention obviates to a large extent the necessity of wearing in the cylinder by use, as it provides means for wearing off the sharp edges of the abrasion marks,y and thus burnishing the cylinder wall as a final, or nishing step, in the reconditioning of worn and out of round cylinders. After reground cylinders have. been burnished with my improved device they are smooth, and require very little wearing in. Obviously, the piston rings are thus subjected to no more than normal wear when first operated in a reground cylinder and will. function efciently for a longer time than otherwise. It is a further object of the invention to provide a burnishing brush that may be substituted for the abrasive element in a Sunnen cylinder grinder of the type shown in my co-pending application Serial No. 233,788, led November 1?,

i 1927, so that a singlevholder will sufiice for per'- forming both the grinding and burnishing operations. Further vand other advantages will be better apparent from a detailed description of the invention in connection with the accompanying drawing, in which:

Figure 1 is a side elevation yof my improved burnishng device with parts of the brush holder (ci. iis-) and parts lof one of the brushes broken away; Fig. 2 is a horizontal cross-section of the device taken on the zig-zag line 2-'2 of Fig. 1; 3 is a front elevation of one of the brushes with parts broken away to show the bristle retaining 33 strip within the brush body; Fig. is a longitudinal section through the brush taken on the line 4- 4 of Fig. 3; Fig. 5 is a greatly enlarged cross-section through a fragment of cylinder Wall showing the abrasion marks on .the inner surface 55 lthereof before the cylinder wall thas been burnished by my improved device; and Fig. 6 is an enlarged cross-section'through the same cylinder wall portion after the said cylinder wall has been burnished. 79

Referring to the drawing, 1 represents the tool holder of a Sunnen cylinder grinder of the type described in the above referred to patent application, said holder being suspended by yoke 2 and collar 3 from a shaft The collar 3 7.5 is pivotallyconnected to the holder l by means of s'tuds 5, 5, and the yoke 2 is pivotally connected to the collar by means of studs 6, 6, so that a universal ljoint connection is farmed between the shaft '4 and the holder 1. The hoicler l is provided with a longitudinally disposed axial bore 'l within which is housed a pinion shaft 8 rotatable by means of the adjusting headV g for the purpose of extending and retracting the brushes 10, 10. The construction and the @Si operation of the tool holder, comprising the parts just described, is substantially the same as that of the holder of my`honing device described in detail in the. aforesaid patent application and will -not be further described herein except inso- 93 far as necessary to explain the operation of the burnishing, elements, or brushes 10, 10.

Each of the brushes 10 comprises a body portion 11 from the back of which toothed pins or rack bars 12,12 project, said rack bars sup- 9.5

porting the brush in the holder'l byvirtue of spaced openings 13,13 (there being a pair of such openings for each brush) in which the rack bars are mounted. It will be observed that openings v 13 intersect the bore 1 and the teeth of pinion l0@ 8 project intoeach of said openings 13 so that they will mesh with the teeth t of each rack bar 12, whereby the rack bars are simultaneously. moved inwardly or outwardly with the rotation of the pinion 8 so as to effect uniform adjustment 195 of the brushes to fit thecylinde'r C Within which they arev being operated. The mounting of the brushes and the method of adjusting the same is the same as that employed when abrasive elements are used, as described in the application 1w structed so that they will be interchangeable with the abrasive elements. Thus a mechanic need have but a single holder with his set of grindingtools, or abrasive elements, and burnishing elements.v After he has performed the rough grinding operation upon a cylinder, followed up by the smooth grinding operation he replaces the grindingelements with the burnishing elements, or brushes 10, whereupon the burnishing operation is performed in exactly the same manner that the grinding operations were performed.

The specific manner of constructing the brush is immaterial, although I illustrate in Figures 3 and 4 a construction that is durable and otherwise very satisfactory.. The brush body 11 is provided with side walls 14, 14 bent inwardly so as to crimp between them a kerfed plate or bristle strip 15 having notches 16 formed from .one end to the other in uniformly spaced relation on both edges. Bristle tuits` 17 are disposed in the notches 16, said tufts being arranged in pairs so thatl l the bristles comprising 'opposite tufts are comnosed of wires common to` both tufts, said wires passing under the strip15. The wires are rmly pinched vand held between the strip 15 and the back of brush body 11 by the side walls' 14, 1,4 ofthe brush body, as shown in the drawing (Fig. 2).` The longitudinal spacing of the tufts 17 is suiiiciently close so that, the'bristles of one vtuft will run into those of the next .adjacent tuft, thus forming a continuous line of )bristles from one end of the brush to the other. The tufts are also sufficiently close to eachother laterally so that when looking at the face of the brush one will see a substantially solid mass of bristle'points.

From the foregoing description it is apparent referred to, and in practice the brushes are conmore or less assume the contour shown in Figure 6. That these sharp abrasive marks are actually worn off is apparent by a microscopic inspection of the cylinder surface. The smoothness of the ,cylinder wall after burnlshing the same with my improved burnishing device is also apparent to the touch when said cylinder wall is carefully felt both before the finishing operation and after the iinishing operation.

' In order to provide the necessary stiffness to eifect the burnishing operation above described the bristles making upthe tufts 17 are preferably of hard steel (that is, harder than the wall of the cylinder) and short enough so as not to bend over when appliedV to the cylinder wall. In other words, the ends of the bristles must bear against the wall with considerable pressure as the brush is rotated in contact therewith.

Having described my invention, I claim:

A burnishing brush comprising a channelshaped body portion, a bristle retaining. strip in the channel of the body portion and having marginal notches, bristle tuftsvlboped around said crimped inwardly to hold the strip and bristle tufts securely tothe body portion.

JOSEPH SUNNEN. 

